Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs)

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What are ADUs?

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Accessory Dwelling Units (ADUs) have been known by many names: granny flats, in-law units, backyard cottages, secondary units and more. No matter what you call them, ADUs are an innovative, affordable, effective option for adding much-needed housing in California. HCD is the state’s leader on local ADU ordinances, which — while optional — have grown exponentially in number as more cities, counties, and homeowners become interested in ADUs as one solution to increasing the supply of affordable housing.

What are the benefits of ADUs?

What are JADUs?

Junior Accessory Dwelling Units (JADUs) are allowed to be created within the walls of a proposed or existing single-family residence and shall contain no more than 500 square feet. JADUs offer additional housing options. They may share central systems, contain a basic kitchen utilizing small plug-in appliances, may share a bathroom with the primary dwelling, all to reduce development costs. JADUs present no additional stress on utility services or infrastructure because they simply repurpose existing space within the residence and do not expand the dwellings planned occupancy.

New! New laws effective January 1, 2020

The Legislature further updated ADU and JADU law effective January 1, 2020 to clarify and improve various provisions in order to promote the development of ADUs and junior accessory dwelling units (JADUs). These include allowing ADUs and JADUs to be built concurrently with a single-family dwelling, opening areas where ADUs can be created to include all zoning districts that allow single-family and multifamily uses, modifying fees from utilities such as special districts and water corporations, limited exemptions or reductions in impact fees, and reduced parking requirements. Please see the Accessory Dwelling Unit Technical Assistance memo (PDF) for more information.

Other recent updates to state laws for ADUs

Effective January 1, 2019

As of January 1, 2019, homeowners who created accessory dwelling units (ADUs) without the required building permits may have the opportunity to bring their ADUs into compliance. For ADUs that were constructed without building permits, local building officials now have the option to inspect an ADU and apply the building standards that were in effect at the time the unit was constructed. This bill: SB 1226 (Bates), adds Section 17958.12 to the California Health and Safety Code Opens in New Window , and with application of appropriate building codes, may allow issuance of a building permit for the residential unit.

Webinar : Recent Legislation "Nuts and Bolts"


 

Technical Assistance Booklet

Information for cities, counties, other local government bodies, and homeowners interested in adding an accessory dwelling unit to their property.

Please note: The ADU Memorandum booklet is currently under construction to reflect recent changes to ADU law which became effective January 1, 2020.

City and county ADU ordinances and HCD review letters

Cities and counties are not required to create ordinances for ADUs; however, any city/county that does adopt an ADU ordinance, must submit the ordinance to HCD within 60 days.

Sample materials from cities and counties

Additional guidance

Research

External websites

You'll find additional resources at the following websites, which are hosted by partners who contributed to HCD's Technical Assistance Booklet.